Military occupation is effective provisional control of a certain power over a territory which is not under the formal sovereignty of that entity, without the volition of the actual sovereign. The intrinsically temporary nature of occupation, when no claim for permanent sovereignty is made by the occupying entity, distinguishes occupation from both colonialism or annexation.

From the second half of the 18th century onwards, international law has come to distinguish between the military occupation of a country and territorial acquisition by invasion and annexation, the difference between the two being originally expounded upon by Emerich de Vattel in The Law of Nations (1758). The distinction then became clear and has been recognized among the principles of international law since the end of the Napoleonic wars in the 19th century. These customary laws of belligerent occupation which evolved as part of the laws of war gave some protection to the population under the military occupation of a belligerent power.